Process for the control of bacteria



PROCESS FOR THE CONTROL OF BACTERIA Edward 0. Bennett, Houston, Tex.,and Edward B. Hodge, Terre Haute, Ind., assignors to Commercial SolventsCorporation, New York, N.Y., a corporation of Maryland No Drawing. FiledOct. 3, 1958, Ser. No. 765,033 7 Claims. (Cl. 2528.55)

Our invention relates to the control of bacteria in water floodingoperations used in the secondary recovery of petroleum oils, and moreparticularly, to controlling such organisms by incorporating into theflooding water effective amounts of nitropolyesters having the followingstructural formula:

ll NO:O (CHzO CR):

where R is selected from the group consisting of hydrogen and alkylhaving up to 20 carbon atoms.

US. Patent No. 2,839,467 lists many of the problems found in thesecondary oil recovery art and the means whereby some of these problemshave been solved. The problem of controlling sulfate reducing bacteriais ever present and always diflicult, as the growth of themicroorganisms is not controlled by economically practicable amounts ofmany bactericides generally utilized in bacterial control and themicroorganisms sometimes become resistant to generally usedbactericides.

The problems attending the control of other microorganisms are moreeasily solved but are, nevertheless, present. These microorganisms aregenerally controlled by moderate amounts of known bactericides.

We have now discovered that noxious microorganisms are economicallycontrolled by our above described nitropolyesters. Compounds which wehave found to be operative in our process include tris(formoxymethyl)nitromethane, tris(propionoxymethyl) nitromethane, tris- (acetoxymethyl)nitromethane, tris(stearoxymethy1) nitromethane and tris(butyroxymethyl)nitromethane, etc.

The usual procedure for treatment of water to be utilized in floodingoperations is to produce a concentrate of the bactericide in water andthen continuously inject this concentrate into the Water to be used inflooding operations at a rate which forms a desired dilution of thebactericide. This is done prior to pumping the water into the oilbearing subterranean formation.

Sampling and checking of the water for sulfate reducing bacterial willshow whether the chemical concentration needs to be raised or may belowered to control effectively the bacteria count of the flooding water.

Alternately, the bactericides utilized in our process may be added tothe oil bearing formations periodically, for example, once a week, as ahigh potency concentrate or the undiluted bactericide may be injectedinto the formation.

We have found that the compounds utilized in our process are activeagainst some strains of bacteria in water at concentrations as low asabout 10-25 p.p.m. However, we prefer to utilize concentrations inexcess of about 50-100 ppm. as we have found that even resistant strainsof Desulfovibrio desulfuricans are eflectively controlled at theseconcentrations.

It is to be understood, of course, that not all of the compounds used inour process are effective to the same degree. The following table setsout concentrations at tris(butyroxymethyl) nitromethane- I .2which-weihave found representative nitropolyesters to be completely eflective against a resistant strain of Desulfovibrio desulfuricans in-water flooding operations.

TABLE Effective Con- Nitropolyesters centratlons tris (formoxymethyl)nitromethane tris(propionoxymethyl) nitromethane 250 tris(acetoxymethyl)nltromethane.. 1, 000 tris (stearoxymethyl) nitromethane. l, 000

The following example sets out the procedure used in 0 testingournitropolyesters for the controlof sulfate reducing microorganisms. Itis not intended that our invention be limited to the exact compositionsor concentrations shown. Rather it is intended that all equivalentsobvious to those skilled in the art be included within the scope of ourinvention as claimed.

Example I In a water treatment plant, a concentrate containingtris(formoxymethyl) nitromethane is continually added to water to bepumped into a subterranean oil bearing formation at such a rate that a100 ppm. solution of the nitropolyester is formed. The nitropolyestertreated flooding water is pumped into the oil bearing formation and iscompletely effective in preventing bacterial plugging of the oil bearingsands and the piping system ll NOz-C (CHzO CR):

where R is selected from the group consisting of hydrogen and alkylhaving up to 20 carbon atoms, to inhibit the growth of bacterial withinsaid formations.

3. The process of claim 2 wherein the nitropolyester is tris(formoxymethyl) nitromethane.

4. The process of claim 2 wherein the nitropolyester istris(propionoxymethyl) nitromethane.

5. The process of claim 2 wherein the nitropolyester" is tris(acetoxymethyl) nitromethane.

6. The process of claim 2 wherein the nitropolyester is tris(stearoxymethyl) nitromethane.

7. The process of claim 2 wherein the nitropolyester istris(butyroxymethyl) nitromethane.

(References on following page) References Cited in the file of thispatent 2,651,590 2,692,231 UNITED STATES PATENTS 2,839,467 1,198,040Landau Sept. 12, 1916 1,873,732 Adams Aug. 23, 1932 5 2,402,776Robinette June 25, 1946 107,419 2,419,021 Harnden Apr. 15, 1947 421,189

. 4 Karstefl Sept. 8, 1953 Stayner et a1. Oct. 19, 1954 Hutchison et a1June 17, 1958 FOREIGN PATENTS Australia May 25, 1939 Italy Mar. 19, 1947

1. IN THE PROCESS OF SECONDARY OIL RECOVERY CHARACTERIZED BY THE STEP OFINJECTING FLOODING WATER INTO OIL BEARING SUBTERRANEAN FORMATIONS TODISPLACE PORTIONS OF THE RESIDUAL OIL THEREIN, THE IMPROVEMENT WHICHCOMPRISES HAVING PRESENT IN THE SAID INJECTED FLOODING WATER IN EXCESSOF 10-25 P.P.M. OF A NITROPOLYESTER HAVING THE FOLLOWING STRUCTURALFORMULA: